21157534 has 8 divisors (see below), whose sum is σ = 31831488. Its totient is φ = 10547040.

The previous prime is 21157529. The next prime is 21157573. The reversal of 21157534 is 43575112.

It is a happy number.

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

It is a super-2 number, since 2×21157534² = 895282489922312, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15022 + ... + 16369.

It is an arithmetic number, because the mean of its divisors is an integer number (3978936).

Almost surely, 2^21157534 is an apocalyptic number.

21157534 is a deficient number, since it is larger than the sum of its proper divisors (10673954).

21157534 is a wasteful number, since it uses less digits than its factorization.

21157534 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31730.

The product of its digits is 4200, while the sum is 28.

The square root of 21157534 is about 4599.7319487118. The cubic root of 21157534 is about 276.5805796580.

The spelling of 21157534 in words is "twenty-one million, one hundred fifty-seven thousand, five hundred thirty-four".