21951401 has 4 divisors (see below), whose sum is σ = 22152900. Its totient is φ = 21749904.

The previous prime is 21951389. The next prime is 21951409. The reversal of 21951401 is 10415912.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 18284176 + 3667225 = 4276^2 + 1915^2 .

It is a cyclic number.

It is not a de Polignac number, because 21951401 - 2¹⁸ = 21689257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21951409) 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, 100586 + ... + 100803.

It is an arithmetic number, because the mean of its divisors is an integer number (5538225).

Almost surely, 2^21951401 is an apocalyptic number.

It is an amenable number.

21951401 is a deficient number, since it is larger than the sum of its proper divisors (201499).

21951401 is a wasteful number, since it uses less digits than its factorization.

21951401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201498.

The product of its (nonzero) digits is 360, while the sum is 23.

The square root of 21951401 is about 4685.2322247675. The cubic root of 21951401 is about 279.9974532081.

The spelling of 21951401 in words is "twenty-one million, nine hundred fifty-one thousand, four hundred one".