21631528 has 8 divisors (see below), whose sum is σ = 40559130. Its totient is φ = 10815760.

The previous prime is 21631517. The next prime is 21631541. The reversal of 21631528 is 82513612.

It can be written as a sum of positive squares in only one way, i.e., 20994724 + 636804 = 4582^2 + 798^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×21631528² = 935846007229568, which contains 22 as substring.

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21631496 and 21631505.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1351963 + ... + 1351978.

Almost surely, 2^21631528 is an apocalyptic number.

It is an amenable number.

21631528 is a deficient number, since it is larger than the sum of its proper divisors (18927602).

21631528 is a wasteful number, since it uses less digits than its factorization.

21631528 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2703947 (or 2703943 counting only the distinct ones).

The product of its digits is 2880, while the sum is 28.

The square root of 21631528 is about 4650.9706513802. The cubic root of 21631528 is about 278.6307641554.

The spelling of 21631528 in words is "twenty-one million, six hundred thirty-one thousand, five hundred twenty-eight".