21501066 has 16 divisors (see below), whose sum is σ = 43056000. Its totient is φ = 7158048.

The previous prime is 21501059. The next prime is 21501079. The reversal of 21501066 is 66010512.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4510 + ... + 7958.

It is an arithmetic number, because the mean of its divisors is an integer number (2691000).

Almost surely, 2^21501066 is an apocalyptic number.

21501066 is an abundant number, since it is smaller than the sum of its proper divisors (21554934).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21501066 is a wasteful number, since it uses less digits than its factorization.

21501066 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4493.

The product of its (nonzero) digits is 360, while the sum is 21.

The square root of 21501066 is about 4636.9241960593. The cubic root of 21501066 is about 278.0694838652.

Adding to 21501066 its reverse (66010512), we get a palindrome (87511578).

The spelling of 21501066 in words is "twenty-one million, five hundred one thousand, sixty-six".