402551021 has 2 divisors, whose sum is σ = 402551022. Its totient is φ = 402551020.

The previous prime is 402550979. The next prime is 402551029. The reversal of 402551021 is 120155204.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 355134025 + 47416996 = 18845^2 + 6886^2 .

It is a cyclic number.

It is not a de Polignac number, because 402551021 - 2¹⁴ = 402534637 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 402550984 and 402551002.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (402551029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 201275510 + 201275511.

It is an arithmetic number, because the mean of its divisors is an integer number (201275511).

Almost surely, 2^402551021 is an apocalyptic number.

It is an amenable number.

402551021 is a deficient number, since it is larger than the sum of its proper divisors (1).

402551021 is an equidigital number, since it uses as much as digits as its factorization.

402551021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 402551021 is about 20063.6741650177. The cubic root of 402551021 is about 738.3693219564.

The spelling of 402551021 in words is "four hundred two million, five hundred fifty-one thousand, twenty-one".