21747957 has 32 divisors (see below), whose sum is σ = 37330944. Its totient is φ = 10929600.

The previous prime is 21747953. The next prime is 21747983. The reversal of 21747957 is 75974712.

It is not a de Polignac number, because 21747957 - 2² = 21747953 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21747953) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5643 + ... + 8679.

It is an arithmetic number, because the mean of its divisors is an integer number (1166592).

Almost surely, 2^21747957 is an apocalyptic number.

It is an amenable number.

21747957 is a deficient number, since it is larger than the sum of its proper divisors (15582987).

21747957 is a wasteful number, since it uses less digits than its factorization.

21747957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3089.

The product of its digits is 123480, while the sum is 42.

The square root of 21747957 is about 4663.4704888098. The cubic root of 21747957 is about 279.1297683863.

The spelling of 21747957 in words is "twenty-one million, seven hundred forty-seven thousand, nine hundred fifty-seven".