21531716 has 6 divisors (see below), whose sum is σ = 37680510. Its totient is φ = 10765856.

The previous prime is 21531709. The next prime is 21531721. The reversal of 21531716 is 61713512.

It can be written as a sum of positive squares in only one way, i.e., 21529600 + 2116 = 4640^2 + 46^2 .

It is a super-2 number, since 2×21531716² = 927229587809312, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2691461 + ... + 2691468.

It is an arithmetic number, because the mean of its divisors is an integer number (6280085).

Almost surely, 2^21531716 is an apocalyptic number.

It is an amenable number.

21531716 is a deficient number, since it is larger than the sum of its proper divisors (16148794).

21531716 is a wasteful number, since it uses less digits than its factorization.

21531716 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5382933 (or 5382931 counting only the distinct ones).

The product of its digits is 1260, while the sum is 26.

The square root of 21531716 is about 4640.2280116391. The cubic root of 21531716 is about 278.2015514735.

The spelling of 21531716 in words is "twenty-one million, five hundred thirty-one thousand, seven hundred sixteen".