402021551 has 4 divisors (see below), whose sum is σ = 423180600. Its totient is φ = 380862504.

The previous prime is 402021541. The next prime is 402021611. The reversal of 402021551 is 155120204.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-402021551 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (402021541) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10579496 + ... + 10579533.

It is an arithmetic number, because the mean of its divisors is an integer number (105795150).

Almost surely, 2^402021551 is an apocalyptic number.

402021551 is a deficient number, since it is larger than the sum of its proper divisors (21159049).

402021551 is a wasteful number, since it uses less digits than its factorization.

402021551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21159048.

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

The square root of 402021551 is about 20050.4750816533. The cubic root of 402021551 is about 738.0454574762.

Adding to 402021551 its reverse (155120204), we get a palindrome (557141755).

The spelling of 402021551 in words is "four hundred two million, twenty-one thousand, five hundred fifty-one".