21867261 has 16 divisors (see below), whose sum is σ = 31530240. Its totient is φ = 13400640.

The previous prime is 21867221. The next prime is 21867277. The reversal of 21867261 is 16276812.

It is not a de Polignac number, because 21867261 - 2⁷ = 21867133 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21867221) 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, 9535 + ... + 11603.

It is an arithmetic number, because the mean of its divisors is an integer number (1970640).

Almost surely, 2^21867261 is an apocalyptic number.

It is an amenable number.

21867261 is a deficient number, since it is larger than the sum of its proper divisors (9662979).

21867261 is a wasteful number, since it uses less digits than its factorization.

21867261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2356.

The product of its digits is 8064, while the sum is 33.

The square root of 21867261 is about 4676.2443263799. The cubic root of 21867261 is about 279.6392505494.

The spelling of 21867261 in words is "twenty-one million, eight hundred sixty-seven thousand, two hundred sixty-one".