151856021 has 4 divisors (see below), whose sum is σ = 151903500. Its totient is φ = 151808544.

The previous prime is 151856009. The next prime is 151856027. The reversal of 151856021 is 120658151.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5712100 + 146143921 = 2390^2 + 12089^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-151856021 is a prime.

It is a super-2 number, since 2×151856021² = 46120502227904882, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (151856027) 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, 18566 + ... + 25463.

It is an arithmetic number, because the mean of its divisors is an integer number (37975875).

Almost surely, 2^151856021 is an apocalyptic number.

It is an amenable number.

151856021 is a deficient number, since it is larger than the sum of its proper divisors (47479).

151856021 is an equidigital number, since it uses as much as digits as its factorization.

151856021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47478.

The product of its (nonzero) digits is 2400, while the sum is 29.

The square root of 151856021 is about 12322.9875030368. The cubic root of 151856021 is about 533.5117704586.

The spelling of 151856021 in words is "one hundred fifty-one million, eight hundred fifty-six thousand, twenty-one".