21037557 has 8 divisors (see below), whose sum is σ = 29017440. Its totient is φ = 13541360.

The previous prime is 21037537. The next prime is 21037559. The reversal of 21037557 is 75573012.

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 21037557 - 2⁸ = 21037301 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21037559) 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, 120819 + ... + 120992.

It is an arithmetic number, because the mean of its divisors is an integer number (3627180).

Almost surely, 2^21037557 is an apocalyptic number.

It is an amenable number.

21037557 is a deficient number, since it is larger than the sum of its proper divisors (7979883).

21037557 is a wasteful number, since it uses less digits than its factorization.

21037557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 241843.

The product of its (nonzero) digits is 7350, while the sum is 30.

The square root of 21037557 is about 4586.6716690864. The cubic root of 21037557 is about 276.0567909811.

The spelling of 21037557 in words is "twenty-one million, thirty-seven thousand, five hundred fifty-seven".