21531526 has 4 divisors (see below), whose sum is σ = 32297292. Its totient is φ = 10765762.

The previous prime is 21531493. The next prime is 21531527. The reversal of 21531526 is 62513512.

It is a semiprime because it is the product of two primes.

It is a super-2 number, since 2×21531526² = 927213223777352, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21531526.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5382880 + ... + 5382883.

It is an arithmetic number, because the mean of its divisors is an integer number (8074323).

Almost surely, 2^21531526 is an apocalyptic number.

21531526 is a deficient number, since it is larger than the sum of its proper divisors (10765766).

21531526 is a wasteful number, since it uses less digits than its factorization.

21531526 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10765765.

The product of its digits is 1800, while the sum is 25.

The square root of 21531526 is about 4640.2075384620. The cubic root of 21531526 is about 278.2007331698.

The spelling of 21531526 in words is "twenty-one million, five hundred thirty-one thousand, five hundred twenty-six".