21386407 has 16 divisors (see below), whose sum is σ = 25477632. Its totient is φ = 17569440.

The previous prime is 21386399. The next prime is 21386429. The reversal of 21386407 is 70468312.

It is not a de Polignac number, because 21386407 - 2³ = 21386399 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21381407) 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, 17808 + ... + 18970.

It is an arithmetic number, because the mean of its divisors is an integer number (1592352).

Almost surely, 2^21386407 is an apocalyptic number.

21386407 is a deficient number, since it is larger than the sum of its proper divisors (4091225).

21386407 is a wasteful number, since it uses less digits than its factorization.

21386407 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1278.

The product of its (nonzero) digits is 8064, while the sum is 31.

The square root of 21386407 is about 4624.5439775182. The cubic root of 21386407 is about 277.5743144312.

The spelling of 21386407 in words is "twenty-one million, three hundred eighty-six thousand, four hundred seven".