21221690 has 32 divisors (see below), whose sum is σ = 43956864. Its totient is φ = 7225920.

The previous prime is 21221671. The next prime is 21221693. The reversal of 21221690 is 9612212.

It is a super-2 number, since 2×21221690² = 900720252912200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21221693) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10025 + ... + 11955.

It is an arithmetic number, because the mean of its divisors is an integer number (1373652).

Almost surely, 2^21221690 is an apocalyptic number.

21221690 is an abundant number, since it is smaller than the sum of its proper divisors (22735174).

21221690 is a wasteful number, since it uses less digits than its factorization.

21221690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2102.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 21221690 is about 4606.7005546269. The cubic root of 21221690 is about 276.8598560372.

The spelling of 21221690 in words is "twenty-one million, two hundred twenty-one thousand, six hundred ninety".