21957513 has 8 divisors (see below), whose sum is σ = 29383488. Its totient is φ = 14584944.

The previous prime is 21957511. The next prime is 21957527. The reversal of 21957513 is 31575912.

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

It is not a de Polignac number, because 21957513 - 2¹ = 21957511 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21957511) 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, 12381 + ... + 14042.

It is an arithmetic number, because the mean of its divisors is an integer number (3672936).

Almost surely, 2^21957513 is an apocalyptic number.

It is an amenable number.

21957513 is a deficient number, since it is larger than the sum of its proper divisors (7425975).

21957513 is a wasteful number, since it uses less digits than its factorization.

21957513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26703.

The product of its digits is 9450, while the sum is 33.

The square root of 21957513 is about 4685.8844415969. The cubic root of 21957513 is about 280.0234376639.

The spelling of 21957513 in words is "twenty-one million, nine hundred fifty-seven thousand, five hundred thirteen".