21445651 has 2 divisors, whose sum is σ = 21445652. Its totient is φ = 21445650.

The previous prime is 21445643. The next prime is 21445657. The reversal of 21445651 is 15654412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21445651 - 2³ = 21445643 is a prime.

It is not a weakly prime, because it can be changed into another prime (21445657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10722825 + 10722826.

It is an arithmetic number, because the mean of its divisors is an integer number (10722826).

Almost surely, 2^21445651 is an apocalyptic number.

21445651 is a deficient number, since it is larger than the sum of its proper divisors (1).

21445651 is an equidigital number, since it uses as much as digits as its factorization.

21445651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4800, while the sum is 28.

The square root of 21445651 is about 4630.9449359715. The cubic root of 21445651 is about 277.8303875405.

The spelling of 21445651 in words is "twenty-one million, four hundred forty-five thousand, six hundred fifty-one".