21995451 has 6 divisors (see below), whose sum is σ = 31771220. Its totient is φ = 14663628.

The previous prime is 21995447. The next prime is 21995453. The reversal of 21995451 is 15459912.

21995451 is a `hidden beast` number, since 21 + 99 + 545 + 1 = 666.

It is not a de Polignac number, because 21995451 - 2² = 21995447 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21995453) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1221961 + ... + 1221978.

Almost surely, 2^21995451 is an apocalyptic number.

21995451 is a deficient number, since it is larger than the sum of its proper divisors (9775769).

21995451 is a wasteful number, since it uses less digits than its factorization.

21995451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2443945 (or 2443942 counting only the distinct ones).

The product of its digits is 16200, while the sum is 36.

The square root of 21995451 is about 4689.9308097242. The cubic root of 21995451 is about 280.1846188905.

The spelling of 21995451 in words is "twenty-one million, nine hundred ninety-five thousand, four hundred fifty-one".