21453961 has 2 divisors, whose sum is σ = 21453962. Its totient is φ = 21453960.

The previous prime is 21453937. The next prime is 21453967. The reversal of 21453961 is 16935412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21344400 + 109561 = 4620^2 + 331^2 .

It is a cyclic number.

It is not a de Polignac number, because 21453961 - 2⁷ = 21453833 is a prime.

It is not a weakly prime, because it can be changed into another prime (21453967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10726980 + 10726981.

It is an arithmetic number, because the mean of its divisors is an integer number (10726981).

Almost surely, 2^21453961 is an apocalyptic number.

It is an amenable number.

21453961 is a deficient number, since it is larger than the sum of its proper divisors (1).

21453961 is an equidigital number, since it uses as much as digits as its factorization.

21453961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6480, while the sum is 31.

The square root of 21453961 is about 4631.8420741644. The cubic root of 21453961 is about 277.8662685120.

The spelling of 21453961 in words is "twenty-one million, four hundred fifty-three thousand, nine hundred sixty-one".