15400021 has 16 divisors (see below), whose sum is σ = 19062400. Its totient is φ = 12115008.

The previous prime is 15399997. The next prime is 15400031. The reversal of 15400021 is 12000451.

It is a cyclic number.

It is not a de Polignac number, because 15400021 - 2¹¹ = 15397973 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is a junction number, because it is equal to n+sod(n) for n = 15399974 and 15400010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15400031) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20470 + ... + 21208.

It is an arithmetic number, because the mean of its divisors is an integer number (1191400).

Almost surely, 2^15400021 is an apocalyptic number.

It is an amenable number.

15400021 is a deficient number, since it is larger than the sum of its proper divisors (3662379).

15400021 is a wasteful number, since it uses less digits than its factorization.

15400021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 988.

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 15400021 is about 3924.2860497166. The cubic root of 15400021 is about 248.7943065611.

Adding to 15400021 its reverse (12000451), we get a palindrome (27400472).

The spelling of 15400021 in words is "fifteen million, four hundred thousand, twenty-one".