21237461781 has 8 divisors (see below), whose sum is σ = 28356001920. Its totient is φ = 14138614752.

The previous prime is 21237461779. The next prime is 21237461789. The reversal of 21237461781 is 18716473212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21237461781 - 2¹ = 21237461779 is a prime.

It is a super-2 number, since 2×21237461781² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21237461789) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4920760 + ... + 4925073.

It is an arithmetic number, because the mean of its divisors is an integer number (3544500240).

Almost surely, 2^21237461781 is an apocalyptic number.

It is an amenable number.

21237461781 is a deficient number, since it is larger than the sum of its proper divisors (7118540139).

21237461781 is an equidigital number, since it uses as much as digits as its factorization.

21237461781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9846555.

The product of its digits is 112896, while the sum is 42.

The spelling of 21237461781 in words is "twenty-one billion, two hundred thirty-seven million, four hundred sixty-one thousand, seven hundred eighty-one".