421972921 has 2 divisors, whose sum is σ = 421972922. Its totient is φ = 421972920.

The previous prime is 421972907. The next prime is 421972979. The reversal of 421972921 is 129279124.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 416160000 + 5812921 = 20400^2 + 2411^2 .

It is a cyclic number.

It is not a de Polignac number, because 421972921 - 2⁹ = 421972409 is a prime.

It is a super-2 number, since 2×421972921² = 356122292114544482, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (421972981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210986460 + 210986461.

It is an arithmetic number, because the mean of its divisors is an integer number (210986461).

Almost surely, 2^421972921 is an apocalyptic number.

It is an amenable number.

421972921 is a deficient number, since it is larger than the sum of its proper divisors (1).

421972921 is an equidigital number, since it uses as much as digits as its factorization.

421972921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 37.

The square root of 421972921 is about 20541.9794810529. The cubic root of 421972921 is about 750.0580227703.

The spelling of 421972921 in words is "four hundred twenty-one million, nine hundred seventy-two thousand, nine hundred twenty-one".