21172744 has 32 divisors (see below), whose sum is σ = 40629600. Its totient is φ = 10341760.

The previous prime is 21172733. The next prime is 21172757. The reversal of 21172744 is 44727112.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 93159 + ... + 93385.

It is an arithmetic number, because the mean of its divisors is an integer number (1269675).

Almost surely, 2^21172744 is an apocalyptic number.

It is an amenable number.

21172744 is a deficient number, since it is larger than the sum of its proper divisors (19456856).

21172744 is a wasteful number, since it uses less digits than its factorization.

21172744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 453 (or 449 counting only the distinct ones).

The product of its digits is 3136, while the sum is 28.

The square root of 21172744 is about 4601.3850088859. The cubic root of 21172744 is about 276.6468410496.

Adding to 21172744 its reverse (44727112), we get a palindrome (65899856).

It can be divided in two parts, 2 and 1172744, that added together give a triangular number (1172746 = T₁₅₃₁).

The spelling of 21172744 in words is "twenty-one million, one hundred seventy-two thousand, seven hundred forty-four".