21900394 has 8 divisors (see below), whose sum is σ = 33983460. Its totient is φ = 10572576.

The previous prime is 21900391. The next prime is 21900397. The reversal of 21900394 is 49300912.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21900391) and next prime (21900397).

It can be written as a sum of positive squares in 2 ways, for example, as 18966025 + 2934369 = 4355^2 + 1713^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21900391) 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, 188739 + ... + 188854.

Almost surely, 2^21900394 is an apocalyptic number.

21900394 is a deficient number, since it is larger than the sum of its proper divisors (12083066).

21900394 is a wasteful number, since it uses less digits than its factorization.

21900394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 377624.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 21900394 is about 4679.7856788533. The cubic root of 21900394 is about 279.7804145734.

The spelling of 21900394 in words is "twenty-one million, nine hundred thousand, three hundred ninety-four".