15400921 has 4 divisors (see below), whose sum is σ = 15465600. Its totient is φ = 15336244.

The previous prime is 15400897. The next prime is 15400939. The reversal of 15400921 is 12900451.

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: 12900451 = 139 ⋅92809.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15400921 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 15400892 and 15400901.

It is not an unprimeable number, because it can be changed into a prime (15400951) 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, 31981 + ... + 32458.

It is an arithmetic number, because the mean of its divisors is an integer number (3866400).

Almost surely, 2^15400921 is an apocalyptic number.

It is an amenable number.

15400921 is a deficient number, since it is larger than the sum of its proper divisors (64679).

15400921 is an equidigital number, since it uses as much as digits as its factorization.

15400921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64678.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 15400921 is about 3924.4007185811. The cubic root of 15400921 is about 248.7991531024.

The spelling of 15400921 in words is "fifteen million, four hundred thousand, nine hundred twenty-one".