45721981 has 2 divisors, whose sum is σ = 45721982. Its totient is φ = 45721980.

The previous prime is 45721937. The next prime is 45722003. The reversal of 45721981 is 18912754.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 45441081 + 280900 = 6741^2 + 530^2 .

It is a cyclic number.

It is not a de Polignac number, because 45721981 - 2⁷ = 45721853 is a prime.

It is a super-2 number, since 2×45721981² = 4180999093128722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 45721981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (45721681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 22860990 + 22860991.

It is an arithmetic number, because the mean of its divisors is an integer number (22860991).

Almost surely, 2^45721981 is an apocalyptic number.

It is an amenable number.

45721981 is a deficient number, since it is larger than the sum of its proper divisors (1).

45721981 is an equidigital number, since it uses as much as digits as its factorization.

45721981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20160, while the sum is 37.

The square root of 45721981 is about 6761.8030879345. The cubic root of 45721981 is about 357.5814762053.

The spelling of 45721981 in words is "forty-five million, seven hundred twenty-one thousand, nine hundred eighty-one".