21372091 has 8 divisors (see below), whose sum is σ = 23451120. Its totient is φ = 19355232.

The previous prime is 21372089. The next prime is 21372103. The reversal of 21372091 is 19027312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21372091 - 2¹ = 21372089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21372011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14821 + ... + 16198.

It is an arithmetic number, because the mean of its divisors is an integer number (2931390).

Almost surely, 2^21372091 is an apocalyptic number.

21372091 is a deficient number, since it is larger than the sum of its proper divisors (2079029).

21372091 is a wasteful number, since it uses less digits than its factorization.

21372091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31085.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 21372091 is about 4622.9958901128. The cubic root of 21372091 is about 277.5123647874.

The spelling of 21372091 in words is "twenty-one million, three hundred seventy-two thousand, ninety-one".