21372351 has 48 divisors (see below), whose sum is σ = 38610432. Its totient is φ = 10232640.

The previous prime is 21372343. The next prime is 21372353. The reversal of 21372351 is 15327312.

It is not a de Polignac number, because 21372351 - 2³ = 21372343 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21372353) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 32710 + ... + 33356.

It is an arithmetic number, because the mean of its divisors is an integer number (804384).

Almost surely, 2^21372351 is an apocalyptic number.

21372351 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21372351 is a deficient number, since it is larger than the sum of its proper divisors (17238081).

21372351 is a wasteful number, since it uses less digits than its factorization.

21372351 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 692 (or 681 counting only the distinct ones).

The product of its digits is 1260, while the sum is 24.

The square root of 21372351 is about 4623.0240103205. The cubic root of 21372351 is about 277.5134901323.

Adding to 21372351 its reverse (15327312), we get a palindrome (36699663).

The spelling of 21372351 in words is "twenty-one million, three hundred seventy-two thousand, three hundred fifty-one".