21957497 has 8 divisors (see below), whose sum is σ = 22320000. Its totient is φ = 21597264.

The previous prime is 21957493. The next prime is 21957503. The reversal of 21957497 is 79475912.

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

It is a cyclic number.

It is not a de Polignac number, because 21957497 - 2² = 21957493 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21957491) 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, 39143 + ... + 39699.

It is an arithmetic number, because the mean of its divisors is an integer number (2790000).

Almost surely, 2^21957497 is an apocalyptic number.

It is an amenable number.

21957497 is a deficient number, since it is larger than the sum of its proper divisors (362503).

21957497 is an equidigital number, since it uses as much as digits as its factorization.

21957497 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1135.

The product of its digits is 158760, while the sum is 44.

The square root of 21957497 is about 4685.8827343415. The cubic root of 21957497 is about 280.0233696481.

The spelling of 21957497 in words is "twenty-one million, nine hundred fifty-seven thousand, four hundred ninety-seven".