153690721 has 4 divisors (see below), whose sum is σ = 154047744. Its totient is φ = 153333700.

The previous prime is 153690703. The next prime is 153690737. The reversal of 153690721 is 127096351.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 127096351 = 41 ⋅3099911.

It is a cyclic number.

It is not a de Polignac number, because 153690721 - 2²¹ = 151593569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (153690751) 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, 177865 + ... + 178726.

It is an arithmetic number, because the mean of its divisors is an integer number (38511936).

Almost surely, 2^153690721 is an apocalyptic number.

It is an amenable number.

153690721 is a deficient number, since it is larger than the sum of its proper divisors (357023).

153690721 is an equidigital number, since it uses as much as digits as its factorization.

153690721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 357022.

The product of its (nonzero) digits is 11340, while the sum is 34.

The square root of 153690721 is about 12397.2061771998. The cubic root of 153690721 is about 535.6517761663.

The spelling of 153690721 in words is "one hundred fifty-three million, six hundred ninety thousand, seven hundred twenty-one".