155279021 has 4 divisors (see below), whose sum is σ = 160633500. Its totient is φ = 149924544.

The previous prime is 155278979. The next prime is 155279041. The reversal of 155279021 is 120972551.

It is a happy number.

155279021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 120972551 = 7 ⋅17281793.

It can be written as a sum of positive squares in 2 ways, for example, as 80802121 + 74476900 = 8989^2 + 8630^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-155279021 is a prime.

It is a super-2 number, since 2×155279021² = 48223148725436882, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155279041) 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, 2677196 + ... + 2677253.

It is an arithmetic number, because the mean of its divisors is an integer number (40158375).

Almost surely, 2^155279021 is an apocalyptic number.

It is an amenable number.

155279021 is a deficient number, since it is larger than the sum of its proper divisors (5354479).

155279021 is an equidigital number, since it uses as much as digits as its factorization.

155279021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5354478.

The product of its (nonzero) digits is 6300, while the sum is 32.

The square root of 155279021 is about 12461.1003125727. The cubic root of 155279021 is about 537.4906676584.

The spelling of 155279021 in words is "one hundred fifty-five million, two hundred seventy-nine thousand, twenty-one".